The present invention relates generally to gas turbine engine structures, and more particularly to an improved stator vane structure for a gas turbine engine providing additional control of power level and velocity diagram efficiency which may be demanded of aviation gas turbines, without using devices for mechanical variation of turbine stator geometry.
In existing turbine engine structures, additional control may typically be achieved by varying the corrected flow of the turbine by mechanically varying stator geometry either by pivoting the stator airfoils or by varying blockage of the stator flow passages with mechanical plugs.
The improved turbine stage structure of the invention yields control of the corrected flow by routing additional flow through internal intraflow ducts between the pressure and suction surfaces of the stator airfoils. The ducts are sized and oriented so that flow therethrough is re-introduced into the gas flow to the rotor in a preselected amount and momentum to produce a change in the main gas flow angle to the desired corrected flow.
The invention may find use in improving fuel efficiency of large fighter engines without sacrificing specific thrust when the engine is operated at maximum power, and in large gas turbine propulsion engines for high speed transport aircraft, where thrust levels required to maintain supersonic flight speeds require high levels of specific thrust, but range requirements demand low levels of specific fuel consumption.
It is therefore a principal object of the invention to provide an improved gas turbine engine structure.
It is a further object of the invention to provide an improved turbine stator airfoil structure for a gas turbine engine.
It is another object of the invention to provide an improved turbine structure for a gas turbine engine wherein the gaseous flow to the rotor is improved by directing a selected portion of the gaseous flow through the stator vanes.
These and other objects of the invention will become apparent as a detailed description of representative embodiments proceeds.